Feasibility of producing blastospores of Beauveria bassiana on different liquid media and its pathogenicity against Tetranychus urticae under laboratory conditions

In the present study, the effects of different supplementary ingredients on blastospore production of entomopathogenic fungus Beauveria bassiana (Bals.) Vuill. Strain IRAN 1395C were evaluated. In the first step, effects of extracts of different agricultural products including rice bran, wheat bran, barley bran, maize bran, and potato waste on blastospore production were evaluated. Our findings revealed that the medium containing rice bran extract provides the best conditions for sporulation. Then, different supplementary proteins including whey, soybean, and egg white with a concentration of 4% were added into the rice bran medium, and their effects on blastospore production were investigated. Different proteins had no positive effects on sporulation. In the last step, effects of adding different chloride salts (KCl, MgCl2, and CaCl2) to the selected culture medium on the increase of blastospore production was studied. The results obtained indicated that use of calcium chloride (CaCl2) had the highest effectiveness on blastospore production than other salts tested. Finally, the pathogenicity of blastospores obtained from liquid medium and conidia harvested from solid culture was compared on Tetranychus urticae Koch. The bioassay output revealed no statistical differences between the pathogenicity of blastospore obtained in liquid medium (LC50 = 3.29 × 106 Blastospore/ml) with conidium produced in solid medium (LC50 = 3.23 × 106 Conidium/ml). The present findings revealed that liquid media could be so helpful for developing mass rearing programs of B. bassiana.